A website of a greeting card vendor provides a graphical user interface (GUI) for marketing greeting cards. A customer uses the GUI to upload a photograph and select a greeting card template. The website combines the photograph with the template to yield a customized greeting card that the customer can purchase. The customer also uploads recipient addresses, selects a card template, selects an envelope template, and selects a font for printing the addresses on the envelope template. The user submits an online request to purchase envelopes that match the selected envelope template and that are imprinted with the uploaded addresses in the user-selected font. Before printing the purchased envelopes, the GUI displays a computer-generated preview of each envelope that will be printed, with each preview showing the respective envelope with a respective one of the uploaded addresses. Each address appears on the previewed envelope as the address will appear on the actual printed envelope.